Objective



L. BERTELE OBJECTIVE Oct. 2, 1934.

Filed July 1933 tiaaa'cn 210mm J): ran i 171'.

Patented Oct. 2, 1934 UNITED STATES PATENT OFFICE OBJECTIVE GermanyApplication July 3, 1933, Serial No. 678,817 In Germany July 8, 1932 1Claim.

While endeavoring to improve the photographic objectives in such amanner that besides a high aperture of about 1:1.4 also a large picturefield is obtained, it has been discovered that it is, indeed, possibleto attain a high aperture, as well as a large picture angle, but thereremain always comparatively great residual deficiencies, especiallyspherical, as well as comatic aberrations.

The object of the present invention is to obviate also said deficiences,and I attain the object in view by providing in the last or rearcomponent of the set of lenses constituting the objective a stronglycurved cemented face which has a collective effect and the curvature ofwhich is directed towards the film.

The invention is illustrated diagrammatically and by way of example inthe accompanying drawing in which Figure 1 shows an arrangement andcombination of lenses rendering the desired effect and constituting,therefore a solution of the problem, and Figure 2 shows the sphericalaberation curves pertaining to the set of lenses shown in Fig. 1, thecurve I having been attained without the strong influence produced by avery strong cementing surface, and the curve II having been obtainedwith the coaction of such a surface.

In Fig. 1 the set of lenses comprises a front component comprising, inturn, four lenses, and a rear component compr sing, in turn, threelenses. The lenses constituting the front component are the plane-convexlens Li(d1) having the convex face 11 and the plane face 12; themeniscus lens Lz(d2) having the convex face rs and the cemented concaveface 11;; the biconvex lens L3(d3l having the two cemented convex faces1'4 and T5; and the biconcave lens L4(d4) having also said cementedhollow face 15 and the hollow face Te which is in contact with the air.The lens L1 is made of a very strongly refractive kind of glass, asappears from the numerical statement nd=1.6375 in the example at the endof this specification, and the lens L4 is made of a. kind of glass thathas likewise a very high refractive index, as appears from the numericalstatement nd=1.6890 in said example, but besides, also its colorseparating capacity is very strong, as appears from the numericalstatement 11:31 in the said example. The lenses constituting the rearcomponent are the plano-concave lens L5(d5) having the plane face n andthe cemented hollow face Ta; the biconvex lens Ila-(d6) having likewisethe cemented convex face T8 and the cemented convex face 11;; andfinally, the meniscus lens L1(d1) having likewise the cemented hollowface 1'9 and the convex face 7'10 which is in contact with the air. Thecemented face Ta is the strongly curved face that is directed towardsthe film.

The letter d indicates the thickness of the lenses in the middle of thesame.

The letter 3 denotes an iris diaphragm which is located between thelenses L4 and L5.

The film must be assumed to be located righthand from the objective.

The numerical data for the example shown in the drawing and describedabove are as follows:

1:1 .5-f=100picture angle about 42 A great-rapidity objective having anaperture of about 121.4 and comprising seven lenses separated from oneanother by two air spaces and forming a front member (L1) consisting ofa very highly refractive glass; a rear member (L5, L6, L1) comprisingthree lenses cemented together two of these three lenses being negativeones and the third being a positive one and enclosed between said twonegative lenses, one of these latter and said positive lens having acemented surface very strongly curved towards the film and having aradius of curvature which is smaller than one-half of the focal lengthof the objective; and a meniscal middle member comprising three lenses(L2, L3, L4) cemented together, the strongly effective negative lensconsisting of a glass having a highly refractive index and a strongcolor-separating capacity.

LUDWIG BERTELE.

